Cyclic Ethers Heterocyclic:Oxygen is part of the ring. .Epoxides (oxiranes) ·Oxetanes C ·Furans (Oxolanes ·Pyrans〔）(Oxanes .Dioxanes Chapter 14 11
Chapter 14 11 Cyclic Ethers • Heterocyclic: Oxygen is part of the ring. • Epoxides (oxiranes) H2C CH2 O • Oxetanes O • Furans (Oxolanes ) O O • Pyrans (Oxanes ) O O •Dioxanes O O
Epoxide Nomenclature ·Name the starting alkene and add“oxide”. peroxybenzoic acid cyclohexene oxide The oxygen can be treated as a substituent (epoxy)on the compound. Use numbers to specify position. o 1,2-epoxycyclohexane Chapter 14 12
Chapter 14 12 Epoxide Nomenclature • Name the starting alkene and add “oxide”. H cyclohexene oxide peroxybenzoic acid O H H O H 1,2-epoxycyclohexane • The oxygen can be treated as a substituent (epoxy) on the compound. Use numbers to specify position
Epoxide Nomenclature (Continued) The three-membered oxirane ring is the parent (oxygen is 1,the carbons are 2 and 3).Substituents are named in alphabetical order. H、XCH3 CH3CH2 H trans-2-ethyl-3-methyloxirane Chapter 14 13
Chapter 14 13 Epoxide Nomenclature (Continued) • The three-membered oxirane ring is the parent (oxygen is 1, the carbons are 2 and 3). Substituents are named in alphabetical order. trans-2-ethyl-3-methyloxirane O H H CH3 CH3CH2
IR Spectroscopy of Ethers IR:The C-O stretch is in the fingerprint region around 1000-1200 cm-1. Many compounds have the C-O stretch. If the IR spectrum has the C-O stretch but does not have a C=O or an OH stretch,then the compound is most likely an ether. Chapter 14 14
Chapter 14 14 IR Spectroscopy of Ethers • IR: The C—O stretch is in the fingerprint region around 1000–1200 cm-1 . • Many compounds have the C—O stretch. • If the IR spectrum has the C—O stretch but does not have a C═O or an OH stretch, then the compound is most likely an ether
MS Spectrometry of Ethers a Cleavage R千CH2一O-R'T R· not observed H oxonium ion Copyright2010 Pearson Prentice Hall,Inc. Main fragmentation is the a-cleavage to form the resonance-stabilized oxonium ion. Either alkyl group can be cleaved this way. Chapter 14 15
Chapter 14 15 MS Spectrometry of Ethers • Main fragmentation is the -cleavage to form the resonance-stabilized oxonium ion. • Either alkyl group can be cleaved this way